docs: def Bond(rhol, rhog, sigma, L):
      r'''Calculates Bond number, `Bo` also known as Eotvos number,
      for a fluid with the given liquid and gas densities, surface tension,
      and geometric parameter (usually length).
  
      .. math::
          Bo = \frac{g(\rho_l-\rho_g)L^2}{\sigma}
  
      Parameters
      ----------
      rhol : float
          Density of liquid, [kg/m^3]
      rhog : float
          Density of gas, [kg/m^3]
      sigma : float
          Surface tension, [N/m]
      L : float
          Characteristic length, [m]
  
      Returns
      -------
      Bo : float
          Bond number []
  
      Examples
      --------
      >>> Bond(1000., 1.2, .0589, 2)
      665187.2339558573
  
      References
      ----------
      .. [1] Green, Don, and Robert Perry. Perry's Chemical Engineers' Handbook,
         Eighth Edition. McGraw-Hill Professional, 2007.
      '''
      return (g*(rhol-rhog)*L**2/sigma)